1. Field of the Invention
This invention relates to improvements in stuffing boxes and more particularly, but not by way of limitation, to a self-aligning, self-lubricating stuffing box for either reciprocating polish rods of producing oil and/or gas well bores, or the like or with rotatable pump rods.
2. Description of the Prior Art
Many producing oil and/or gas well bores are provided with down-hole pumping apparatus operable for elevating the well fluids to the surface of the ground. The usual down-hole pumping apparatus is actuated by a surface mounted pump jack assembly which is connected with the down-hole pump by a polish rod or sucker rod string which extends longitudinally through the well bore into connection with the pump means. The reciprocation of the sucker rod string or polish rod by the pump jack actuates the pump for elevating the well fluids through the well tubing for delivery through the usual pumping "T" for recover of the fluids. It is common practice to install stuffing box around the outer periphery of the polish rod above the pumping "T" for precluding loss of the well fluids around the outer periphery of the polish rod. The stuffing box is normally provided with packing means engageable with the outer periphery of the polish rod, and as the polish rod reciprocates with respect to the packing means, considerable friction may be generated between the polish rod and the packing. It is important that an efficient lubrication of the packing means be achieved in order to reduce damage of the packing means by the frictional heat generated.
The normal stuffing box in widespread use today normally comprises a housing surrounding the outer periphery of the polish rod for containing the packing members and usually includes means for adjusting the pressure of the packing members against the outer periphery of the polish rod. In the event there is any misalignment between the pumping "T" and the pump jack, damage may occur, and it is advantageous to correct any misalignment for improving the overall fluid producing operation. At the present time this misalignment is usually corrected by squeezing the packing sufficiently to force the polish rod into proper alignment, or to squeeze the packing around one side of the rod to prevent leakage of fluid. This solution to the problem frequently results in damage or accidental destruction of the packing means when the pump jack is shut down and the polish rod string is suspended therefrom. In addition, the fluid weight on the packing gland may compress the packing excessively, squeezing out any lubricant which may be present in the packing. As a result the packing is frequently damaged upon a "start up" of the pump jack.
The Reeves U.S. Pat. No. 3,468,374, issued Sept. 23, 1969, and entitled "Self-Cooled Oil Well Polish Rod Stuffing Box" has been devised to overcome the problem developed by frictional heat or inadequate lubrication of the stuffing box. The Reeves stuffing box includes a cooling surrounding the polish rod and interposed between upper and lower packing glands for assuring an adequate supply of lubricating fluid for the rod during reciprocation thereof. The Reeves device, however, has not addressed the problem of misalignment between the pump jack and the pumping "T". Accordingly, the improvement of the aforementioned application Ser. No. 483,101, incorporates a swivel connection and alignment bushings in combination with the improved lubrication system of the Reeves patent. One disadvantage of the Reeves lubrication system, however, is the fact that the fluid supply line and fluid return line between the cooling chamber and the lubricant source are both disposed exteriorly of the stuffing box housing and in some installations these exterior conduits or hoses are subject to damage during the operation conditions of the stuffing box.